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New Aluminium Alloy Pre-Treatment Project to Launch

Thu, 30 May, 2024

TWI is launching a new Joint Industry Project (JIP) to investigate sustainable approaches for the surface pre-treatment of aluminium alloys, including for parts that are additively manufactured.

This project, which is now open for sponsors to join, aligns with the industry need to use environmentally benign, REACH compliant coatings to reduce the risk of corrosion damage of critical components, particularly in the aerospace and defence sectors.

Industry Requirements

The project team recognises the increasing use of additively manufactured aluminium alloy parts in aerospace, defence, automotive, and other industries. Additive manufacturing offers a number of benefits due to the potential to produce intricate, light weight and low cost components. Chemical conversion coatings have been widely used as a surface pre-treatment, but the restrictions placed on hexavalent chromium (Cr VI) and replacement of phosphate coatings means suitable alternatives need to be found.

EU (REACH, Annex XIV, SVHC list) and United States restrictions on the use of Cr(VI) coatings have been put in place because of environmental and health concerns but, where they are permitted for use, they costly and difficult to apply.


This JIP, ‘Sustainable Approaches to Surface Pre-treatment of Additively Manufactured Aluminium Alloys,’ will address these concerns by investigating viable REACH-compliant, Cr(VI)-free coating replacements as well as identifying Cr(VI)-free paint systems comprising a REACH-compliant surface pre-treatment, primer, and top coat.

These investigations will deliver industrial guidance on the corrosion performance of various pre-treatments when exposed to different environments, as well as how microstructural variations in AM aluminium alloys and traditional cast and wrought alloys influence pre-treatment performance, durability, and reliability.

Tests will evaluate corrosion performance, adhesive bonding characteristics, and thermal cycling resistance, to generate insights into suitable Cr(VI)-free surface pretreatments and REACH compliant paint systems, enabling the development of guidelines for their selection for industrial applications.


This JIP will deliver a number of benefits including increased coating durability and reliability, which will reduce costly unplanned maintenance, improve asset availability, and increase longevity of components based on AM aluminium alloys.

This project will also help reduce the barriers to the adoption of AM technologies, bringing further inherent benefits from the increased use of additive manufacturing, as well as improving the competitiveness and environmental responsibility of different industry sectors.

Increased confidence in the use of commercially available REACH compliant Cr(VI)-free products through an independent assessment of performance will also lead to reduced costs via sustainable and environmentally friendly solutions, with less regulatory burden and hazardous waste costs.

Of course, there are also the more general health, safety and environmental benefits of eco-friendly corrosion protection options to be considered too.

Find Out More

You can find out more about the benefits, need, objectives and deliverables of this project, as well as how you can join and gain access to the work package reports, project updates, and a final report by downloading the PDF, below:

PROP311400 Sustainable Approaches to Surface Pretreatment of Additively Manufactured Aluminium Alloys - pdf - 567kb

For more information please email: